The Energy Balance

Earth gets all its energy from the Sun and loses energy into space If more energy is lost into space than is received from the Sun, the planet gets cooler. If it loses less energy than it receives, the planet will warm up.

Have you noticed that it is often cooler when there are clouds in the sky? Some types of clouds act like giant sun umbrellas, shading the Earth and reflecting the sunlight that hits them. Other types of clouds act like a jacket, holding the heat in and preventing it from leaving the atmosphere. Today, most clouds act more like a sun umbrella and help keep our climate cool. However, this could change if global warming affects the type of clouds, their thickness, and how much water or ice they contain.

While it might be quite warm in the countryside on a summer day, it can get unbearably hot in a nearby city! That’s because the buildings and pavement in cities absorb oodles of sunlight, much more than the countryside. These cities are called “heat islands.” The countryside is also cooled by water evaporating from lakes and given off by the plants in forests and fields. Cities have fewer plants and bodies of water and so are not cooled very much by evaporation.